The present invention relates to an improved tufted surface covering and method.
Tufted surface coverings are employed indoors as floor coverings in the form of carpeting, area rugs, floor, gym, barrier and crash mats, as well as outdoors, in the form of carpeting, artificial turf, cushioned sport and play surfaces and sport mats. Surface coverings for sporting use are generally constructed by stitching into a preformed fabric backing layer to form tufts, and then bonding the primary backing layer to an impact-absorbing resilient lower layer or shock pad, by means of a thin, laminating layer.
Conventional tufting machines employ rows of needles, which are threaded with a suitable yarn fed from a ball or creel through an aperture adjacent the tip of each needle. The tufting machine forces the rows of needles through a backing fabric. The needles pierce the fabric from back to front, pushing the yarn through the backing. Looping tools catch the yarn loops on the face of the backing as the needles are withdrawn. Once tufting of the primary backing is completed, the loops of face yarn are generally cut to form a pile surface or xe2x80x9cfacexe2x80x9d. While the loops may be left uncut for indoor carpet surfaces, the loops of surfaces intended for outdoor usage are generally cut in order to produce a covering more closely resembling grass. The diameter of the yarn, the number of yarn strands in each tuft, and the spacing of the tufts determine the density of the final surface.
A woven or nonwoven fabric web is generally employed as a tufting base or primary backing layer. A laminating layer of glue, rubber or synthetic resin must be applied over the exposed loops to lock the tufts into the fabric interstices or punctured holes and to bond the backing layer to a shock absorbing layer. Alternatively, a secondary layer may be laminated to the primary layer. The tufted loops on the underside of the primary layer may also be melted to form a button, which secures the loops, but does not seal them. Such sealing is necessary in order to retain the tufts in place to withstand the stresses associated with usage as well as to seal in surface coverings intended for outdoor use against the entry of water. Entry of moisture into the needle holes surrounding the tufts, followed by repeated freeze-thaw cycles, would eventually damage the covering.
The use of fabric webs, elastomeric tufting layers and laminating layers all serve to spread the force of any impact to the surface covering. This dissipation of force affects the traction and torque characteristics of the covering. For this reason, although known synthetic turf surfaces may be constructed to visually resemble natural grass turf, they are not functionally equivalent. The characteristics of play associated with a sport differ on synthetic turf from the play on natural turf. For example, the cleats on athletic footwear do not purchase on synthetic surfaces in the same manner as on natural turf. Balls striking synthetic surfaces bounce higher, retain their spin and travel farther than on natural turf.
There are also certain weaknesses of dimensional stability associated with surface coverings constructed by laminating multiple layers. Each layer of the laminate has discrete physical properties which are determined by its composition. For example, each layer expands and contracts at a different rate. Use of hydrophilic or hydroscopic materials may also introduce moisture into one or more lamina of the covering.
In addition, known artificial turf surfaces demonstrate limited ability to withstand the heavy wear and substantial stresses associated with high impact sports over extended periods of time. In sports such as golf, cricket, field hockey, polo and la Crosse, which employ clubs, bats and sticks, force is applied tangentially across the upper layer of a synthetic turf. Because such laminated sport surfaces do not provide significant horizontal movement, these tangential forces can cause the turf to delaminate with wear. In the case of laminated golf mats, lack of horizontal elasticity may actually cause the carpet layer to melt to the club upon striking.
Thus, there is a need for a tufted surface covering which can withstand both the vertical and horizontal forces associated with athletic use, which seals the tufts in place against wear and water damage and which absorbs the forces of play in a manner similar to natural turf.
The present invention provides a greatly improved surface covering having a tufted impact-absorbing layer. This construction provides tufts which are securely anchored against wear and sealed against weather in a covering having efficient impact absorption without the need for a load-spreading laminating layer. The surface covering of the invention includes a layer of particles of a thermosetting polymer compound mixed with a particle binding agent to form a self supporting web. Thermosetting vulcanized natural and/or synthetic rubber compounds are employed. The polymer layer is tufted with a tufting material and heated to a temperature of from about 100xc2x0 C. to about 220xc2x0 C. at an elevated pressure of up to two tons per square inch, the particle binding agent causing the particles to bind together at elevated temperature and pressure to anchor and seal the tufts in place. Cross-linking agents and polar polymer containing compounds may be employed as particle binding agents. In another aspect of the invention, a second layer of particles of a thermosetting polymer mixed with a particle binding agent may be joined with the particles of the first layer at elevated temperature and pressure. A series of spaced apertures extends through the first and second layers to enable free draining of the surface covering. The lower surface of the covering includes spaced indentations to reduce the weight of the covering.
Objects and advantages of this invention will become apparent from the following description taken in relation to the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of the invention.
The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof.